Method and apparatus for determining distance by echo



A ER 22, 1932 R. FESSENDEN 1,853,119 A METHOD AND APPARATUS FORDETERMINING DISTANCE BY ECHO Original Fild March 28, .1921

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REGINALD A. FESSENDEN, F CHESTNUT HILL, SETTB METHOD AND APPARATUS FORDETERMINING DISTANCE BY ECHO flriginal application filed March 28, 1921,Serial No. 456,112 Divided and this application flied January 9,

1926. Serial No. 80,201. 1

The present application is a division of U. S. Patent No. 1,636,502, andit relates to methods and apparatus for locating the position of objectsby echo particularly their dis tance and direction,

ly the receipt of such echo by means of a flash of light in connectionwith a scale whereby observations may be secured from which the distancefrom a station to the object to be located may be determined. Not onlydoes the present invention have particular application to. measuringdistance and depth beneath the vessel, but may also be applied to themeasurement of heights of an aircraft 35 above the ground from theaircraft itself.

My invention will be understood by reference to the drawings, in which-Figure 1 shows diagrammatically a means for carrying out my inventionFig. 2 being a detail showing the means for supporting the wire. Fig. 3is a section on line 33 of Fig. 2, and

Fig. 4 is an elevation of the scale disk.

In Fig. 1 is shown a method in which the 25 depth is determined bymeasuring the time taken by the sound in traveling the echopath, andalso by measuring the difference of phase or time of the sounds receivedby two receivers. This method is hence also 80 peculiarly adapted fordetermining both the distance and direction of icebergs or mines orderelicts.

In Fig. 1, 11 is the ship. 12 is the waterline and 13 is the bottom ofthe sea or channel. 14 is a sound-producing member here shown as anoscillator, but it may be of any other suitable character, for example aspark gap in oil, an electromagnetized nickel rod, etc. The oscillatoris preferably located in the forepeak tank. 16 is a sound receiver hereshown as a microphone immersed in the tank 15, preferably in a differentcompartment to that containing the sound producer 14, and preferably ina sound shadow so that sounds directly produced by 14 will pass by it.Any other suitable sound receiver may be used.

' The path of the sounds to the bottom and reflected therefrom to thereceiver is indicated by the lines 48 and 47. The electric imand itincludes especialprojection to the left, the

pulses from the receiver 16 go to and throu h the filament 41 of theFessenden pallograp or filament galvanometer, of the types shown inapplicants U. S. Patents N o. 97 9,145 filed December 23, 1907, issuedDecember 20, 1910, N 0. 1,045,782, filed June 16, 1908, issued November26, 1912, and No. 1,172,018, filed March 14, 1908, issued February 15,1916, or through the thin strip of that type of applicants galvanometershown in applicants U. S. Patent No. 1,042,778, filed March 22, 1905,issued October 29 1912.

If the filament type used, the filament is preferably made of gold, andapproximate- 1 one ten thousandth of an'inch in diameter. 05'

pplicant has, contrary to what might be supposed, in view of the greatdensity of gold and its poorer conductivity, found it much superior toall other materials for this purpose. It is much more sensitive thanwires 7c of silver or quartzfibres, for-reasons which applicant does notknow. Also gold wire gives the largest range of readings of any electricinstrument known, i. e. applicant has discovered that a gold filamentgiving unit deflection for one one hundred millionthof an ampere willcarry one one hundredth of .an ampere without. burning out; i. e. willhandle without injury one quadrillion times the energy necessary to giveunit deflection. so Also the wire' being made of chemically pure gold,the filament will work as a relay contact with a similar wire withoutappreciable contact resistance and without chan e of contact resistance,in this respect di ering entirely from all otherrchemically pure metals.

40, 40 are the magnetic poles of the pallograph, and 54 is the lightingand optical system. 37 is a revolving shaft driven through the gears 33,34 by the motor 32, and carrying the disc 38, shown in detail in Fig. 4,where is a projecting portion of the disc 38 carrying ascale 49 asshown, and also the spiral curve 50.. 42 is a revolving disc' mounted ona prolongation of the motor shaft and carrying the contact 51, soarranged that every time the disc 38 comes to the position shown in Fig.2.with the edge of the projecting portion vertical and the circuit ofthe dy- 1 waves as desired namo 39 and oscillator 14 is closed throughthe brushes 44, 45 as shown and the prolongation of the motor shaft 43and contact 51, connected electrically to shaft 43, and a sound emittedby the oscillator; either a single impulse or a train of low or highfrequency and as adapted to the receiving system.

At the instant that the sound is emitted by 14, the wire of thepallograph hanging straight down, no light passes through the openlng401 in the polepiece 40 and the disc 38 is therefore dark and thefigures on its scale are invisible or nearly so. When the emitted soundhas traveled the echo-path 4:6, 47 and actuated the receiver 16, thewire ll is twitched to one side for an instant and the small beam oflight from the small hole in 40 illuminates that particular figure onthe scale which has reached the point opposite to the hole. The reaterthe depth of water, the longer will be t e echo-path, and the longerwill be the portion of the scale which has traveled past the point atwhich the zero of the scale was when the contact 51 sent out the impulseinto the water. Consequently the scale may be graduated to read thedepth of water directly in feet,'and since in practice the disc 38revolves about four times per second, owing to persistence of vision thereading is clear and distinct. The illumination is very sharp, almostinstantaneous, applicant having in his possession clear photographstaken by him with this instrument showing with perfect sharpness anddefinition and in its true undistorted shape each individual wave of agroup of waves emitted from an antenna at a frequency of thirty-onethousand per second. As this would correspond to a difierence in depthof water of less than one inch, it will be evident that very exactsoundings may be made, and in practice the time of illumination of thefigures on the scale is made one or two orders, i. e. ten or one hundredtimes greater.

The object of the spiral reading the scale. shown by the scale, thespiral. will be seen at the top of the illuminated port-ion of-the scaleas a short horizontal line. As the depth increases this short horizontalline will appear to move downward and the depth of water can be told bynoting how far down the short horizontal bar appears from its zero or uprmost position, this being read if desired y another scale. Also thescale poris to obviate tion of the disc 38 may have that-portion of thedisc carrying'the readings between-0 and 10 feet colored red, and thatbetween 10 and 20 colored green.

- Also it is preferred to have the scale read only to 50 fathoms, sothat when the depth is above 50 fathoms the beam of light from the holein 40 will. not strike the projection of the disc 38, but will fall uponthe selenium When the depth is zero as cell 35 connected to the batteryand bell 36, so that as long as the ship'is in safe water the bell willring continuously and its cessation will automatically indicate theshoaling of the water.

The depth reading may be checked by taking a second reading on thereceiver 29. Or, havin determined the distance of an iceber ing itsdistance on the receiver 16 and then on the receiver 29 from which bysimple triangulation its direction may be found.

its direction may be found by first takstill simpler method is to takereadings simulv taneously or in rapid succession on 16 and 29 and noticethe distance apart of the two short horizontal bars which appear in theilluminated portion. This may be done by means of the switch which maybe used to connect receivers 29 and 16 individually or together in thecircuit. This will vary as the cosine of the direction angle, and ifdesired the spiral may be drawn to read directly in degrees. Which sideof the bow the iceberg lies is determined by disconnecting one receiverby raising its key, and noting which bar, i. e. the upper or the lower,disappears. If the lower disappears,'that receiver is nearest theiceberg. The direction of other sounds-may be similarly observed.

What I claim as my invention is:

1. In the art of locating objects by reflected waves, means fortransmitting waves, means for receiving means including in part saidreceiving means for causing an optical indication of the distance of theobject to change in color in accordance with the distance of the object.

2. In the art of locating objects by reflected waves, means for emittingwaves to be refiected, means for receiving the waves so reflected, andmeans for producing thereby an indication of the distance of the objectcomprising a continuous source of illumination and a rotating scalesynchronized with the emission of the emitted wave on which scaleprising a rotating scale synchronize with the emission of the-emittedwave, source of illumination, means tobereobjects by reflected forreceiving the waves so re a continuous. for normally the reflectedwaves,

preventing said illumination from shining on said scale including anelectro-responsive member movable on energization to permit the light toshineon said scale and connections between said receiving means and saidelectro-responsive member for energizing the latter on receipt of thereflected waves.

4. In the art of locating objects byrefiected waves, a continuouslyrotating measuring scale, means for emitting waves to be reflected whensaid measuring scale is in an initial position, means for receiving thewaves so reflected and means 'for producing thereby an indication of thedistance of the object comprising a source of continuous illuminationand means operated by the received waves for causing said illuminationto momentarily illuminate the scale indicating the distance of theobject.

5. In the art of locating objects by reflected waves, a continuouslyrotating measuring scale, means for emitting waves to be reflected whensaid measuring scale is in an initial position, means for receiving thewaves so reflected and means for producing therewith an indication ofthe distance of the object comprising said continuous rotating scale, ashutter and a source of illumination behind said shutter and meansincluding in part said shutter and operated by the received waves forallowing said illumination to shine on said scale.

6. In the art of locating objects by reflected waves, a continuouslyrotating measuring scale, means for emitting waves to be reflected whensaid measuring scale is in an initial position, means for receiving thewaves so reflected and means for indicating when the object is nearerthan a certain distance in- I eluding said rotating scale and a lightsensitive device positioned to be normally shielded by said rotatingscale and means for easting a beam of light on said light sensitivedevice if said reflected waves are received before said rotating scaleshields said light sensitive device and means operated by said beam forgiving an alarn.

7 The method of. determining depths and distances by the aid of a'soundproducer,

, sound receiver and indicating means which consists in producing thesound waves, allowing them to travel to the object whose distance is tobe measured and be reflected, detecting the reflected sound waves,producing by means of the detected wave a momentary illumination of acontinuously rotating scale synchronized with the emission of theemitted wave whereby the measurement indi cated on the scale establishesthe distance to the object.

8. In the art of locating objects by reflected waves, means forreceiving the reflected waves, an indicator having various colorsassociated with definite'distances and means operated by said receivingmeans for illumi: nating said colors in accordance with the distance ofthe object.

' 9. In the art of locating objects by reflected waves, means forreceiving the reflected waves, a rotating indicator having differentcolors associated with different distances and means operated by saidreceiving means for illunlilinating the color corresponding to the de tl O. In the art of locating objects byrefiected waves, means forproducing a wave adapted to be reflected from the object whose distanceis to be measured, a continuously rotating indicating means havingdifferent colors corresponding to'difierent distances, means operatingsaid wave producinng means synchronously associated with said rotatingindicating means, means for receiving said reflected wave and meansoperated upon the reception of said waves to. illuminate the indicatingmeans corresponding to the distance of the object whereby the colorbecomes illuminated corresponding to the distance of the object. 4

11. In the art of locating objectsby reflectedwaves, means forperiodically producing waves adapted to be reflected from the objectwhose distance is to be measured, an independently rotating indicatorada ted to assume different positions corres on ing to the differentdistances that the ob]ect may be distant and means operated by thereceipt of the reflected wave to illuminate a portion of the indicatorwhereby theposition of the indicator illuminated indicates the distanceof the ob'ect.

12. n the art of locating ob'ects by reflected waves, means forerioically producing waves adapted to e reflected from the object whosedistance is to be measured, an independently rotating indicator adaptedto show difi'erent colors corresponding to the difl'erent distances thatthe object may be distant, and means operated by'the receipt of thereflected waves to illuminate a portion of the indicator whereby thecolor showing indicates the distance of the object.

REGINALD A; FESSENDEN.

